Multiple-feed horizontal underfeed stoker



C. F. MILLER.

MULTIPLE FEED HORIZONTAL UNDERFEED STOKER APPLICATION FILED sEPLlQ, 1916.

Patented Sept. 14, 1920.

INVENTOR.

HIS ATTORNEYJIN F'ACT UNITED STATES PATENT OFFICE.

CHARLES MILLER, 01? PITTSBURGH, PENNSYLVANIA, ASSIGNOR T0 WESTING- HOUSE ELECTRIC & MANUFACTURING COMPANY, A. CORPORATION OF PENN- SYLVANIA.

MULTIPLE-FEED HORIZONTAL UNDERFEED STOKER.

Specification of Letters Patent.

Patented Sept. 14, 1920.

A Application filed September 19, 1916. Serial No. 120,978.

To all whom it may com-cm:

Be it known that I Crnxnnns F. MILLER, a citizen of the l -nited States, and a resident of Pittsburgh, in the county of Allegheny and State of Pennsylvania, have made a new and useful Invention in l\lultiple-Feed Horizontal Underfeed Stoker's, of which the following is a specification.

This-invention relates to under-feed stokers and particularly to stokers of that type ordinarily termed horizontal underfeeds and which are provided with horizontal retorts.

An object of the invention is to produce a horizontal type of stoker, in which means are employed, for eliminating the difficulties ordinarily encountered in such stokers by reason of clinkers adhering to the side walls of the furnace.

A further object is to produce a horizontal underfeed stoker in which means are employed for so feeding fuel to the furijace thatthe side walls of the furnace are 110- tected from the heat of combustion by the fuel entering the furnace.

A'further object is to produce an underfeed stoker in which new and improved means are employed for delivering forced draft to the furnace.

A further object is to produce a horizontal under-feed stoker in which improved means are employed for preventing coal or finely divided fuel from dropping from the fuel supporting surfaces into the blast delivery'ducts or passages.

A further object is to produce a new and,

improved grate bar or fuel supporting element for furnaces in which means are employed for adequately cooling the bar and for, at the same time, preheating the air or blast delivered to the fuel bed of the furappa rent throughout the further description of the invention, are attained by means of a stoker embodying the features, and to some extent the details of construction, herein described and illustrated.

In the drawings accompanying and forming a part hereof, Figure 1- is a transverse, vertical. sectional view of a stoker embodying my invention. Fig. 2 is a perspective view of a combined pedestal and spacer member which forms a detail of my invention. Fig. 3 is a fragmental perspective view, illustrating the means employed for mounting the moving and stationary grate bars, which form a part of the stoker illustrated. Fig. 3 is so located, with relation to Fig. 2 of the drawings, that it illustrates the method of mounting the grate bar supporting and actuating elements on the combined pedestal and spacer member.

The stoker illustrated, as an embodiment of my present invention, includes two fuel feeding retorts at, each of which is located immediately adjacent to one side wall of the furnace and is adapted to feed fuel onto and over an adjacent set of moving and stationary grate bars 5. The'grate bars as shown extend at right angles to the longitudinal axis of the retort and, as shown, may be inclined downwardly so that the fuel issuing from the retort is fed over them and is finally discharged on to dump grates (5, which are located between the two sets of grate bars and are adapted to discharge ash and clinker into an ash pit. located below the central portion of the furnace.

As illustrated each retort 4 is substantially orizontal. extends from the front to the re: r of the furnace, and is adapted to receive fuel from a hopper or other receptacle located on the outside and preferably. at the front of the furnace. Any suitable means, such as one or more reciprocating plungers, may be employed for feeding fuel into and through each retort and for forcing the fuel upwardly out of the retort and onto adjacent grate bars. Each retort is mount ed on pedestals 7, which are suitably spaced along the side walls of the furnace and are so constructed as to form a frame which supports side walls 8 and 9 and a base plate 10, which constitute the retort. This is accomplished by making each pedestal 7 more or less U shaped so that it is provided with Cir between the well 8 of the retort, and the adpicent side wall of the turnace. The retort wall 9 is preferably inclinedso that the mouth of the retort is wider than the base. For this reason the wall supporting sin-taco of the arm 12 is inclined. The lower cdge ot each side wall 8 and Elis sdapted to engag'b a separate rib 13, formed on the pedestal 7, whereas the side wullsere bolted or otl'ierwise rigidly secured to the arms of the pedestals. The base plate is shown mounted on the rib emerging flanges of the side walls 8 and 9 andmay be secured in place in any suitable manner. 7 4

Toeach pedestal 7 is secured bybolts or otherwise a spacing member 14- which forms a support for the grate bars 5, of one setand for partition plates 15. The plates 15 divide the space. under each retort und its cooperating set of grate bars, into two compartments or chambers 16 end-17, the former of which may be .termed. the primary air chamber, whereas the latter may be termed the secondary air chamber.

illustrated each spacer member Ll consists of a base 18., two up-rights l9 and 20, and a webor truss member between the uprights. The russ mei'hher consists essentially of two inclined cords :21 and both of which terminate at the lower. ends in a horizontal cord These top cords of the truss member form the supporting surfaces for the partition plates 15. The up-- right 19 torms a. support for it separately formed grnte-borsi'ipporting sir box 2% and the rip-right 2U terminates in 1 lug 25, which forms a support for t member 26 and cooperates with the upper end of the adjacent arm 12, of the pedestal 7, in forming a hear ing for o roclz shaft 27.

The partition plates 15 mounted on the inclined cord members 21, of the spacers. 14:, are adopted to be notched out so that the lug and the upper end the arm 12 project through them, or so thz'it the upper edges of the plates abut against the upper edge of the side an 9 of the retort. For this purpose; 1 have provided the arm l2, of each pedestal, with o. downwardly inclined lzu'zerelly projecting flange 28, which in effect forn'is an extension of the cord member ill and is adapted to secure one notched edge of a plate 15 in place. The

cord member 21 is extended on the other side of the lug 25 or the lug is provided with a laterally projecting inclined flange which forms a corresponding support for the other notched edg', of a plate The partition plates supported on the cord member 22 of the" spacers l-l engage the air box 24. and consequently communication between the air chambers l6 and L7 is absolutely cut on, except through the air box 24- :ind the grate bars as will be described.

The grote bars 5 of each set are mounted boxes Elie member 26 is provided with u laterally"projecting flange which rests upon the upper edges of the lugs 25 ofthc spacers i l and the member itself is boltcdor other wise rigidly secured. to the littoral faces of the lugs. In this way it not only forms o support for the. grate bars but acts e. tic member between the members ll. The air bolt as illustrated is channel shaped and its flung-es project downwardly on opposite sides oi the upper ends of of, the spacers 1%, and are adopted to be rigidly secured to them. With this arrange ment the air box is in open communication with the chamber 16. It is provided in its upperor gm.te-bar-supportingface with u seriesof regularly spaced air delivery ports on one member 26 and one of the air 31, which are adapted to deliver air or blast from the chamber 16 into air formed within the grate bars 5.

As illustrated esch grate bar is with a substantially U which is adapted to communicate at one end with a port 31, of the sir box, through. a. port 33 foimed in the oir-boX-engaging face of the bar and which extends along the inner surface, of the top of the bar "to the inner or retort end of the bar and then back along the lower wall of the bar and. terminates in a. delivery port 34, located adjacent to the air box engaging; end of the her and comn'iunicatingwith one of the secondary air chambers 1'7. in this way sir entering each gruteba-r passes first li-long the upper or fuel supporting wall of the bar and then is reversed and passes buck elong the lower wallof the bar and is finally discharged into it secondary iiir'chamber, from which it is delivered to the fuel bed through air delivery openings between the grate bars 5. Enclngrate bar 5 is also pro vided with twyer openings 35, located at the retort end of the grate bar and commui'iicating with the passage 32. These openings discharge air from the passage 32 into the mass of green fuel as it issues from the retort, and they are preferably-so located in the bars that the blast issuing from them posses across the mouth of the retort.

passages provided shaped air passage Blast is also discharged into the fuel issuing from the retort through twyer opcm lugs 36 located on the opposite side oi the retort. As illustrated the openings 36 are fori'ned in the retort well 8 near its upper edge and extend througlu'iut the length of the retort. These openings communicate with the space between side will 8 and side wall of the furnace and are consequently in open communication with the chamber 16. lnasmuch as the blast entering the fuel bed through these ports is not preheated. it to some extent keeps down the ten'ipernture ot' the fuel bed immediately adjacent to the. side wall of the uprights l9,

the furnace and thereby inof the moving grate bars.

creases its protective effect of the fuel on the side wall.

In the stoker illustrated alternate bars 5 of each set are stationary whereas the intermediate bars are reciprocated longitudinally by means of the rock shaft 27 which may be oscillated byany suitable means, such as a stoker engine located at the front of the furnace. The moving grate bars are operatively connected to the rocker arm by prongs 2T andnot only aid the fuel in its progress from the retort to the dump grates (S'but also agitate the breaking up of the fuel bed andtend'to prevent the formation of large clinkers. It will of course be understood that the grate bar supporting surface of the air box 24'is proportioned to accrannuulate the reciprocation of the moving grate bars and that the ports 31 and 33 formed in the air box and in the grate bars respectively are so proportioned that they will not cut down the flow of air through them at any time during the reciprocation The stationary grate bars are operatively connected to the support members 26 by prongs 26.

The dump grates 6, as illustrated, are pivotally mounted on lugs 38 formed on the air boxes 2%. The free ends of the grate bars 6 are adjacent to each other and the gates are adapted to swing downwardly for the purpose of dumping the ash and refuse material into the ash pit.

The operation of the stoker illustrated, is as follows: Fuel is continuously or periodically fed into each retort 4 at a point below the surface of the fuel maintained within the retort or on the fuel supporting surfaces of the furnace. Fuel entering each retort crowds fuel within the retort upwardly and onto the adjacent grate bars 5. The continual or periodical upheaval of fuel within each retort occasions a crowding action within the fuel bed and causes the fuel bed to distribute itself over the grate bars 5 and dump grates 6. As already described this distributing action is aided by the reciprocation of the moving grate bars, and

to some extent by the inclination of the bars, The blast delivered to the fuel bed is received first by the primary air chamber 16. As illustrated each chamber 16 receives blast from an air duct or passage 39,-which is delivered through the twyer openings 35 formed in the grate bars whereas the remaining portion is delivered through ports 34: to the secondary air chamber 17. The grate bars are so formed that air delivery passages are provided between them. This is accomplished by providing a spacing projection 40 on each side of each end of each grate bar, the projections cooperating to space the grate bars and to provide the necessary air passages between them.

In Fig. l I have illustrated a damper controlled port 43 for delivering air under pressure to the ash pit or below the dump grates G. This port is shown in communi cation with one of the primary air chambers l6 and the damper 424: which controls it may be actuated from the front of the stoker if desired. \Vith this arrangement blast to the ash. pit may be shut off without shutting off the blast to the other parts of the furnace or it may be controlled in such a way that there will be no tendency for the blast to blow holes through the portion of the fuel bed supported on the dump grates.

The dump grates may be actuated from the front of the furnace by any suitable means, and the portion of the furnace above the dump grates is preferably accessible through doors located in the front, and if desired in the rear of the furnace. It will be apparent that coal sifting will have no detrimental effect on the operation of the stoker since it cannot enter the primary air chambers nor is there any possibility for such sifting to interfere with the ope 'ation of the stoker. The fine coal or ash, dropping through the openings between grate bar 5, and the fine coal, dropping through the openings between theretort ends of the grate bars and the upper edges of the retorts, fall into the secondary air chambers 17. The inclined walls of these air chambers cause the siftings to collect on the l'lOl'lZOllllill floor of the chambers from which it may be removed through the doors forn'ied in the front or rear of the furnace as desired. With this arrangement the sifted coal can be readily and quickly rcmoved by merely shutting down the blast while the doors in the front of the furnace are open. 1

(inc of the advantages of the furnace illustrated is that clinkers may be readily removed from the fuel bed and consequently the operation of cleaning the furnace is materially simplified; There is no possibility of the clinkers adhering to the parts of the furnace, since the reciprocations of the moving grate bars will break the clinkers'free from the ends of the grate bars and will also prevent them from adhering to the enposed surfaces of the air box. In cleaning the stoker the. clinkers will preferably be broken up by a punch bar, inserted from 'sions may he mu the trout or possibly Iroin the rear of the hl'OlitPi and alter they are freed troin the portions oi the tool bed supported by the grate bars the dump grates (5 may he dripped thereby discharging all of the ttlinkers and ash into the ash pit-- it the minhers are properly broken up so as to prevent arching across the dump grates, the cleaning of the furnace will be very simple and will not octasion a loss of fuel, since the portion ot the fuel bed supported on the "es 5 rill be freed from the elinlcers and ash prior to the dumping operation and there will he no tendency for it to avalanche into the ash pit. i

Another important teature of my invention is the means employed for introducing the blast or the air into the fuel bed This 7 is accomplished by the form and the arrangement oi the grate hars and IS a mate rial improvement over the blast delivery means of horizontal stolrers now in use and known to me. Another feature of the invention is that the opeating n'leehanism of the moving; grate bars is cooled by the air or hlast entering the furnace. This is aoeomplished by locating it in the secondary air cha1nbers.

(lther features of my invention are,-that toe retorts may he removed from the fun naee without in any way atlect-ing the ad justnient ot the flfitllt bars 5 or at their operupting merhaniszn, and that there is no op portunity for tuel to enter the primary air chamb ll hile l have illustrated and described but one embodiment ot my invention it will he apparent that various changes, substitu tions, modifications, additions, and omis- 2 to in the apparatus illustrated without departing from the spirit and scope ot the invention as forth in the appended claims.

li hat l claim is:

l in an under-teed stoker, grate bars, a horizontal retort, pedestals on which the retort is detaehahly mounted, a rocking;- bar supported by the pedestals for reciprocating some of said grate liars, and means supported by the nedestals for supporting the grate bars indep inlently ot the rocking bar and the ort to 1 retrieval of the rot/art with.) distu liars l an horizontal retortto' and th ,win fuel 15 l l ,4: i 1 ,1 set ()1 grate bars locateu on one side oi the retort each grate bar the set extending into proximity with an upper edge of the retort, a separately tornled pedestal on which the retort, is detaehably mounted, a spaciiig member secured s and on which the grate bars are mounted iiuleoendentlyot' the retort, and partition plates mounted on the pedestal ind spacing member and Llifl 'ig the so. below the a i d pedestal retort and the grate hars into two air chanihers, one of which receives air from the other. i

3. In an under-teed Stoker, a fuel-feeding retort having twyer openings adapted to discharge across the mouth thereof, a dump grate, grate bars receiving "Fuel from the retort and delivering onto the dump grate, means tor (.lividin the space below the grate bars and retort into two compo.rtments and the space below the dump grate into separate compartment, said grate hars having air passages litter-ding;- (.ommunieation between the compartments thereheueath, and means for delivering air from one of the first two compartments to said retort twyer openin s and to the compartment under the dump grate.

t. In an underteed Stoker, a fuel-feeding retort having twyer openings in a side thereof, a dump grate, grate bars adapted to receive fuel from the retort and to deliver onto the dump grate, means for segregating the space immediately below the grate bars from the rest of the space below the fuel supporting elements of the StOl(1, said grate hars having longitudinal air passages COIII- municating with said segregated space and having; twyer opening at the retort ends adapted to discharge an n said )assi across the mouth of the art, means for segregating the saare heh dump grate, and means tor separately air to the g ate liar-passages, to twyer openings, and to the segreg s below the dump grate,

5. in an underfeed stoltciga fuel feeding retort having tw "er openings, a dump grate, grate hars receiving tuel from the retortand delivering onto the dump vgaate, means tor dividing the space immediately below the fuel supporting elements into two eornpartinents, said grate bars being provided with passages adapted to afford communicz with air passages, and means for dividing the space below thestolrer into separate air compartments, a eompartment being located immediately under each set of bars and receiving air passing through the passages in the bars, another compartment beneath each oi said compartments communicating with.

the said passages in the bars and twyers in the retort, and another compartment under the dump grate communicating with one of the last named compartments.

7. A horizontal underfeed stoker, comgrate bars, each set of grate bars having passages in communication with the space therebeneath, means for supplying air under pressure to said grate bar passages, and means for excluding air from the space be low the dump grate.

An underfeed stoker, comprising at least two horizontal retorts extending from the front to the rear of the stoker, a dump grate located between the retorts, a separate set of grate bars between each retort and the dump grate, pedestals on which each retort is mounted, supporting and spacing members secured to the pedestals on which the grate bars of each set are mounted, partition plates mounted on the grate-bar-supporting members, and forming an air chamber, and a fuel sifting receiving chamber below each set of grate bars,'and means for delivering air under pressure chamber.

0. An underfeed stoker, comprising at least two horizontal retorts, extending from the front to the rear of the stoker, a dump grate located between the retorts and ex tending from the front to the rear of the Stoker, grate bars between each retort and the dump grate and provided with air passages, a separate support member for each retort, a separate support member for each set of grate bars, an air box mounted on each grate bar support member, and means for delivering air to each air boX and through the air boxes to passages formed within the grate bars.

10. An under-feed stoker, comprising two horizontal fuel feeding retorts, a dump grate located between the retorts, a separate set of grate bars located between each retort and the dump grate, means for sup porting each retort, means for supporting each set of grate bars independently of the retorts including an air box located ad acent to the dump grate, and partition plates mounted on the grate bar supporting means for dividing the space below each retort and its corresponding grate bars into two air chambers, one of said chambers extending to each from each retort to the air bo.\' and the other extending under one of said last mentioned chambers and one retort.

11. In an underfeed stoker, a fuel feeding retort, an ash discharge mechanism, grate bars provided with twyer openings at the retort ends thereof and with passages in communication with said openings, said grate bars adapted to receive fuel from the retort, supporting means for said grate bars and having air passages contiguous to the ash discharge mechanism and communicating with the grate bar passages, an air delivery chamber below the grate bars, a chamber located below the air delivery chamber and communi ating directly with the grate bar passages through the passages in said supporting means and from which air is delivered through said grate bar passages to the twyer openings and to said air delivery chamber.

12. In an underfeed stoker, a retort, an ash discharge mechanism, grate bars located in parallel relation and extending from the retort to th ash discharge mechanism, an air delivery passage formed in each grate bar, having its inlet at the ash discharge end of the bar and communicating with twyer openings formed in the retort end of the bar and an air delivery port located in the lower face of the bar, a primary air chamber located below the grate bars and communicating directly with the inlets of the air pasformed in the grate bars through a passage independent of the ash discharge mechanism, and a secondary chamber located immediately below the grate bars and between the bars and the primary air chamber and receiving air from the delivery ports 'of the grate bars.

12-3. In an underfeed stokcr, a retort, an ash discharge mechanism, grate bars located in parallel relation and extending from the retort to the ash discharge mechanism, com municating longitudinally extending air passages formed in each bar, a primary air chamber in communication with the grate bar passages for delivering air thereto at the ash discharge end of the grate bar passages and also directly to separate twyers located at the mouth of the retort, and a secondary air chamber located immediately below the grate bars and in communication with the passages thereof and above the primary air chamber for receiving the air delivered to the passages in the grate bars.

' chamber communicating e passages in the s y air chamber .innner below each o1 grate bars and in communication with the thereof for :eceiving air delivered through the passages the grate bars and for delivering the air so received between the grate bars to the fuel 7 supported on the bars.

in an underleed stolrer, a retort, an ash discharge mechanism, grate bars located between the retort and the mechanism for receiving fuel issuing from the retort and discharging the fuel onto the mechanism, each bar being provided with an'air passage and having an inlet at theash discharge end oi the bar, a chamber located below the grate bars and in communication with he passages thereof for receiving air which has traversed the air passages of the bars, a separate chamber located below the ash discharge mechanism, a primary air directly with the inlets of the grate bar passages, and means for delivering" regulable amounts of air from the primary air chamber to the chamber below the ash discharge meclrmism.

16. In combination in a stoker, a retort, a dump grate mec H'AlllSID, grate bars between the retort and the mechanism, support members for the retort, grate bars and dump grate meciianisni, comprising formed pedestals su anortino; the retort se separately fori ned grate bar support members secured to the pedestals, and on which said grate bars and said dump grate mechanism are mounted, and partition plates'mounted on the members and dividing the space below the grate bars and retort into two chain bers which communicate through passages formed in the grate bars.

17. in combination in a Stoker, a retort, an ash discharge mechanism, grate bars extending from the retort toward the ash discharge mechanism, retort pedestals on which the side walls and the base plate of the retort are mounted, a separately formed grate bar supporting member secured to each pedestal, and partition plates mounted on said members and dividing the space below the grate bars into two chambers.

18. In combination in an underiteed stokcr, a retort, anash discharge mechanism, grate bars extending from the retort toward the ash discharge mechanism, separately formed ii-shaped pedestals supporting and consti tuting a mounting frame for the retort sides and base plates, and separately formed grate bar supporting pedestals and on mounted.

In testimony whereof, l have hereunto subscribed my name this 18th day September, 191G. p

RLES F. lvllLLER.

which said grate bars are members secured to said 

